1. Field of the Invention
The invention relates to a system for the analysis of fabric surface appearance, and in particular to a method and apparatus for constructing a three-dimensional image of a fabric surface.
2. Background Information
When assessing the grade of fabric it is desirable to use objective evaluation criteria so that interested parties can be confident in the represented grading. Recent progress in this area has been directed towards developing automated analysis techniques which are effective in identifying surface characteristics, such as pilling, of fabric. Such automated techniques can provide a standard, objective, evaluation of fabric grade.
Current automated techniques include acquiring surface images from a fabric specimen using a Charge-Coupled Device (CCD) camera with a suitable lighting source. The camera produces an image of the fabric surface which is manipulated to identify the different reflex intensity (gray) areas created by pilling and background features. A suitable grey threshold is applied to identify pilling on the fabric surface. Such a technique suffers from the disadvantage of the reflectance not being consistent across patterned, colorful or multicolored fabrics. The reflex intensity of the pilled areas appears different in different color areas of the fabric. Thus, on patterned fabric this technique cannot consistently identify fabric surface characteristics.
To avoid the above problem a laser triangulation technique can be used. In this technique the fabric is placed on an X-Y translation table and the high spots on the fabric surface measured one by one with a laser sensor. However, data capture using this technique is considerably slower than with the CCD camera, and because the technique relies on reflection of a laser beam the technique has limitations of use with dark fabrics.
It is an object of the present invention to provide a system for the analysis of fabric surface appearance that is unaffected by the color or pattern of a fabric.
It is a further object of the present invention to provide a system for the analysis of fabric surface appearance that ameliorates the above-mentioned disadvantages or at least provides the public with a useful alternative.
According to a first aspect of the invention there is provided a system for analyzing fabric surface appearance including a feed mechanism for running a fabric over a crest, an image capturing device operable to capture a plurality of profile images of the fabric surface at the crest, and a computer system in communication with the image capture device and operable to manipulate the images to produce a three-dimensional representation of the fabric surface.
Preferably, The feed mechanism includes a frame for holding the fabric bent to form a crest, and a drive mechanism for moving the frame in a manner that moves the crest in the fabric from one end of the fabric to the other. The frame may be an A-frame, Alternatively, the frame may include at least two rollers, an endless belt disposed between the two rollers, and a drive motor for rotating at least one of the rollers, and wherein the belt has fasteners for removably securing the fabric to it.
Preferably, the image capturing device is a Charge-Coupled Device camera.
According to a second aspect of the invention there is provided a method of analyzing fabric surface appearance including the steps of: capturing a series of profile images of the surface of a fabric and manipulating the images to produce a three-dimensional representation of the fabric surface, identifying prominent characteristics in the three-dimensional representation, and comparing the identified prominent characteristics to reference data to identify a grade for the fabric.
Preferably, the images to produce a three-dimensional representation of the fabric surface includes: applying a threshold to each image to identify the profile edge line of the fabric surface, resolving the profile edge line into data points, and combing the data points from the series of images to produce a three-dimensional map.
Preferably, identifying prominent characteristics in the three-dimensional representation includes: filtering the three-dimensional map, and identifying portions of the three-dimensional map with characteristics above a predetermined height.
Preferably, the reference data includes height, area and distribution density of the prominent characteristics.
According to a third aspect of the invention there is provided a system for analyzing fabric surface appearance including: a feed mechanism for running a fabric over a crest including, a frame for holding the fabric bent to form a crest, and a drive mechanism for moving the frame in a manner that moves the crest in the fabric from one end of the fabric to the other, an image capturing device operable to capture a plurality of profile images of the fabric surface at the crest, and a computer system in communication with the image capture device and operable to manipulate the images to produce a three-dimensional representation of the fabric surface, to identify prominent characteristics in the three-dimensional representation, and to compare the identified prominent characteristics to reference data to identify a grade for the fabric.
Further aspects of the invention will become apparent from the following description, which is given by way of example only.